Generally, microfluidic systems, such as inkjet print heads, have many internal microfluidic channels and paths connected to the ambient environment through inlet and outlet ports. Liquid materials flow through the internal microfluidic channels are dispensed out from a nozzle tip. While the fluid within the system is completely isolated from the ambient environment, the fluid within a nozzle is typically exposed to air and subject to dry, thereby clogging the nozzle and/or internal microfluidic channels to clog, especially at the liquid-air interface. Often, such clogging is uncorrectable, rendering the system no longer usable. FIGS. 1A and 1B are illustrations of scanning electron microscope (SEM) pictures respectively illustrating an exemplary inkjet print head nozzle before and after clogging.
Nozzle clogging or failure affects the functionality and reliability of the respective microfluidic systems and squanders significant time and resources needed to repair or replace such microfluidic systems. For example, when the nozzle failure or clogging happens to a conventional ink printer head, a costly and difficult maintenance/repair process may have to be carried out for declogging of the failed orifices. Sometimes, the clogged nozzle as well as its print head has to be replaced. Furthermore, nozzle failure and clogging problems may hinder the adaptation of microfluidic systems in many biological applications, such as the droplet-on-demand technologies in drug discovery, genomics, and proteomics, or the bio-printing technologies that printing (or dispersing) biomolecules and/or bio-analytical solutions by virtue of the precise volume control and accurate positioning without contact.